During the manufacture of discs, multiple discs are placed on a platform, or pallet, for ease of transport and manufacture. As commonly known in the art, the storage of data on the discs requires that the discs include magnetic layers of material on the surface. Magnetic layers are deposited onto the disc through a process known as sputter deposition. During the sputter deposition, the discs are arranged on the pallet such that the surface which will receive the magnetic layers is facing upwards.
Prior to storing information or depositing magnetic layers on the discs, impurities which may have collected on the surface of the discs must be removed. In addition, any impurities contained on the pallets must also be removed. Typically, the pallets, which are used during multiple deposition, are covered with layers of material which were previously deposited on discs during prior depositions. If not removed, these previously deposited materials can outgas during subsequent heating and deposition, thereby degrading the performance of the magnetic layers.
In some current systems, to remove the impurities from the discs and the pallets, the pallets and the discs are placed in a low pressure vacuum chamber. Placing the pallet and discs in a low pressure vacuum chamber allows high vapor materials, such as water and alcohol, to be removed. However, although high vapor materials are removed, other materials, such as oil and grease are not removed by the low pressure vacuum chamber.
To remove impurities or materials that cannot be removed by the low pressure vacuum alone, some current systems utilize a process known as sputter deposition. Sputter deposition is a process by which high energy ions hit a substrate surface, such as the surface of a pallet, wherein the impact of the ions removes impurities on the surface of the substrate. In these systems, a negative RF bias is applied to the pallet with an RF power supply and the pallets and discs are bombarded with an ion flux, such as, for example, oxygen, argon or carbon dioxide. The ions chemically attack, or react, with the impurities and thereby remove the impurities. These systems, however, suffer in that the sputter deposition not only removes impurities, but can damage the surface of the substrate, such as the pallet or the disc. Further, the use of an RF power supply, which has a high noise factor, increases the danger to personnel and further increases potential electrical problems. A need in the industry exists to increase the rate of reduction, or cleaning rate, of the pallets and discs, while reducing the risks of electrocution of the users or other electrical problems of the apparatus.